An example of a photovoltaic component is disclosed in International patent application publication No. 98/25 312. This publication relates to a conventional photovoltaic component, wherein a p-n junction is formed at the light-receiving side of a p-doped silicon wafer. It is proposed to make an electric contact between the light-receiving side at the backside of the wafer. To this end, the silicon wafer is cut into strips. Each strip is first provided with an n-doped emitter layer that covers all of its surfaces and on top of that layer a passivating layer is arranged. Then a first set of contacts is made on the backsides of the strips, which contacts are p-doped and extend through the passivating layer and the emitter layer into the silicon wafer, and a second set of contacts is made, that are arranged in the slits and extend through the passivating layer into the emitter layer so as to form an electric contact with that emitter layer. The emitter layer and the second set of contacts provide an electric connection between the front side of the silicon wafer to its backside.
Another photovoltaic component is disclosed in German patent application publication No. 195 25 720.
Manufacturing the known photovoltaic component comprises the steps of    (a) providing a silicon wafer having a light-receiving side and an electric bonding side opposite to the light-receiving side with a predetermined basic doping in the form of a p-type doping;    (b) providing the silicon wafer with a passivating layer at the electric bonding side;    (c) making a plurality of grooves arranged one next to the other in the passivating layer at the electric bonding side, which grooves can extend into the silicon wafer;    (d) making at the grooves n-type doping areas in the silicon wafer to obtain n-type semiconductor part-structure;    (e) making a plurality of p-type thick-film electric contacts on the passivating layer, between adjacent grooves to obtain p-type semiconductor part-structure and a contacting part-structure; and    (f) making in each of the grooves a thin film contact to obtain an auxiliary contacting part-structure.
The photovoltaic component is a solar cell that serves to convert electromagnetic energy into electrical energy. The centrepiece of the component is a silicon wafer. The silicon wafer is a flat, mono-crystalline body of silicon with two main surfaces directed opposite to each other. The thickness of the silicon wafer is normally about 160 μm (micrometer) or more, which is substantially smaller than a lateral extension (diameter) of the silicon wafer. The lateral extension of the silicon wafer for example is about 10 cm.
The silicon wafer has silicon as its semiconductor base material. Additionally the silicon wafer has a predetermined basic doping. A predetermined basic doping is understood to mean the introduction of a predetermined dopant or impurity atom into a base material for changing one electrical property of the base material. Doping can result in two types of conductivity, the p-type conductivity and the n-type conductivity. A suitable dopant for silicon is an element of the third main group of the periodic table for producing p-type conductivity and an element of the fifth main group of the periodic table for producing n-type conductivity.
The silicon wafer has a light-receiving side (front side), which can be provided with a texture. When the photovoltaic component is in operation, electromagnetic radiation reaches into the silicon wafer via the light-receiving side. For supplying electric energy to an external circuit an interdigital semiconductor structure is arranged on the electric bonding side (rear side) of the silicon wafer. This semiconductor structure consists of an n-type semiconductor part-structure and a p-type semiconductor part-structure. One of the semiconductor part-structures together with the silicon wafer forms the p-n junctions, which are necessary for the production of the photocurrent.
The semiconductor part-structures are arranged at a predetermined distance to each other. This means that there are no p-n junctions between the interdigital semiconductor part-structures. The semiconductor part-structures are for example grid-like or finger-like. They consist of a plurality of webs, wherein one web of a semiconductor part-structure is separated from a web of the other semiconductor part-structure for example by a groove or an interval. The semiconductor part-structures engage with each other in such a way that one surface is as large as possible, which is produced by the p- and n-conducting semiconductor part-structures arranged opposite each other.
One of the semiconductor part-structures together with the silicon wafer forms a base of the photovoltaic component. The other semiconductor part-structures forms an emitter of the photovoltaic component. For electrically contacting the interdigital semiconductor structure an interdigital contacting structure is mounted on the interdigital semiconductor structure with a semiconductor part-structure for electrically contacting the n-type semiconductor part-structure, and a contacting part-structure for electrically contacting the p-type semiconductor part-structure.